Jump to content

Clearcutting

From Wikipedia, the free encyclopedia

This is an old revision of this page, as edited by AJSingh31 (talk | contribs) at 15:58, 20 November 2012 (→‎See also). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Template:Globalize/Canada

For other uses, see Clearcut (disambiguation).
Clearcutting in Southern Finland

Clearcutting, or clearfelling, is a controversial forestry/logging practice in which most or all trees in an area are uniformly cut down. Clearcutting, along with shelterwood and seed tree harvests, is used by foresters to create certain types of forest ecosystems and to promote select species that require an abundance of sunlight or grow in large, even-age stands.[1] Logging companies and forest-worker unions in some countries support the practice for scientific, safety, and economic reasons. Detractors see clearcutting as synonymous with deforestation, destroying natural habitats[2] and contributing to climate change.[3]Clearcutting is the most popular and economically profitable method of logging. Clear cutting serves a dual purpose: marketing harvested wood and clearing the land for cattle farmers.[4]

Types

Many variations of clearcutting exist; the most common professional practices are:[5]

  • Standard (uniform) clearcut – removal of every stem (whether commercially viable or not), so no canopy remains.
  • Patch clearcut – removal of all the stems in a limited, predetermined area (patch).
  • Strip clearcut – removal of all the stems in a row (strip), usually placed perpendicular to the prevailing winds in order to minimize the possibility of windthrow.[6]
  • Clearcutting-with-reserves – removal of the majority of standing stems save a few reserved for other purposes (for example as snags for wildlife habitat), (often confused with the seed tree method).
  • Slash-and-burn – the permanent conversion of tropical and subtropicals forests for agricultural purposes. This is most prevalent in tropical and subtropical forests in overpopulated regions in developing and least developed countries. Slash-and-burn entails the removal of all stems in a particular area. This is a form of deforestation, because the land is converted to other uses. Slash and burn techniques are typically used by civilians in search of land for living and agricultural purposes. The forest is first clear cut, and the remaining material is burned, releasing harmful greenhouse gases into the atmosphere. These emissions have been linked as direct contributors to global warming. One of the driving forces behind this process is a result of overpopulation and subsequent sprawl. These methods also occur as a result of commercial farming. The lumber is sold for profit, and the land, cleared of all remaining brush and suitable for agricultural development, is sold to farmers.[7]
  • Selective Harvesting – Selective harvesting is perhaps the most environmentally conscious method of logging. Unlike the aforementioned techniques, this method is used solely for harvesting wood. Logs are selectively harvested around old-growth trees, whose durability and long interconnectedness with the ecosystem provide unique habitats for plants and animals. This method of deforestation is intended to preserve the ecosystem while still reaping the benefits of timber harvesting. However, selective harvesting can still cause habitat destruction, fragmentation, and microclimate alteration that can harm the remaining trees and ecosystem.[8]

Clearcutting contrasts with selective cutting, such as high grading, in which only commercially valuable trees are harvested, leaving all others. This practice can reduce the genetic viability of the forest over time, resulting in poorer or less vigorous offspring in the stand.[citation needed] Clearcutting also differs from a coppicing system, by allowing revegetation by seedlings. Additionally, destructive forms of forest management are commonly referred to as 'clearcutting'.

Negative impacts

Clearcutting near Eugene, Oregon

Clearcutting can have major negative impacts, both for humans and local flora and fauna.[9] A study from the University of Oregon found that in certain zones, areas that were clear cut had nearly three times the amount of erosion due to slides. When the roads required by the clearcutting were factored in, the increase in slide activity appeared to be about 5 times greater compared to nearby forested areas.[10] Clearcutting can also lead to an increased possibility of rapid runoff, loss of economic sustainability in that no timber products are available for a long time after clearcutting, loss of habitat for some wildlife species, unattractive visual effect, greater possibility of unwanted shrub and grasses becoming established,[11] as well as a decrease in property values; diminished recreation, hunting, and fishing opportunities.[12]

The worlds rain forests could completely vanish in a hundred years at the current rate of deforestation. Between June 2000 and June 2008 more than 150 000 square kilometers of rain forest were cleared in the Brazilian amazon. While deforestation rates have slowed since 2004, forest loss is expects to continue for the foreseeable future. [13] Farmers slash and burn large parcels of forest every year to create grazing and crop lands, but the forests nutrient-poor soil often renders the land ill-suited for agriculture, and within a year or two, the farmers move on.[14]

Positive perspectives

Clearcutting can be practiced to encourage the growth and proliferation of tree species that require high light intensity.[15] Generally, a harvest area wider than double the height of the adjacent trees will no longer be subject to the moderating influence of the woodland on the microclimate.[1] The width of the harvest area can thus determine which species will come to dominate. Those with high tolerance to extremes in temperature, soil moisture, and resistance to browsing may be established, in particular secondary successional pioneer species.

Clearcutting can be used by foresters as a method of mimicking a natural disturbance and increasing primary successional species, such as poplar (aspen), willow and black cherry in North America. Clearcutting has also proved to be effective in creating animal habitat and browsing areas, which otherwise would not exist without natural stand-replacing disturbances such as wildfires, large scale windthrow, or avalanches.

In temperate and boreal climates, clearcutting can have an effect on the depth of snow, which is usually greater in a clearcut area than in the forest, due to a lack of interception and evapotranspiration. This results in less soil frost, which in combination with higher levels of direct sunlight results in snowmelt occurring earlier in the spring.[16]

Clearcuts are used to help regenerate species that cannot compete in mature forests. A number of them -- aspen, jack pine and, in areas with poor soils, oaks -- are important species for both game and nongame wildlife species.

More recently, forest managers have found that clearcutting oak stands helps regenerate oak forests in areas of poor soil. The tree canopies in oak forests often shade out the ground, making it impossible for newly sprouted oaks to grow. By removing the older trees, the saplings stand a chance of recruiting into the forest. [17]

Clearcutting & the effects on Wildlife

File:Effects of Clearcutting to Wildlife.jpg
Effects of Clearcutting to Wildlife

Clearcutting's main destruction is towards habitats, where it makes the habitats more vulnerable in the future to damage by insects, diseases, acid rain, and wind. Removal of all trees from an area destroys the physical habitats of many species in wildlife. Also clearcutting can contribute to problems for ecosystems that depend on forests, like the streams and rivers which run through them. When it comes to terms of forest biome, community of trees, plants, animals, insects, fungi and lichen all work together to increase each others survival. [18]

The most famous inhabitant is the northern spotted owl [where?]. The bird is one of many that nest in dense forest. Woodpeckers, hawks, bats and flying squirrels and some of the forest animals that lose their homes and hunting grounds as a result of clearcutting. The diversity of animal species is decreased by the removal of mature trees [citation needed].

In Canada ,the black-tailed deer population is at further risk after clearcutting. The dear are food source for wolves and cougars, as well as First Nations Groups and other hunters. While deer may not be at risk in cities and rural countryside, where they can be seen running through neighbourhoods and feeding on farms, in higher altitude areas they require forest shelter. [19]

Environment

Environmental groups criticize clearcutting as destructive to the water, soil, wildlife, and atmosphere, and recommend the use of sustainable alternatives.[20] Clearcutting has a very big impact on the water cycle. Trees hold water and topsoil. Clearcutting in forests removes the trees which would otherwise have been transpiring large volumes of water and also physically damages the understorey of grasses, mosses, lichens ferns etc. All this bio-mass is able to retain water during rainfall. Removal or damage of the biota reduces the local capacity to retain water which can exacerbate flooding and can lead to increased leaching of nutrients from the soil. [citation needed].

Clearcutting also prevents trees from shading riverbanks, which raises the temperature of riverbanks and rivers, contributing to the extinction of some fish and amphibian species [where?]. Because the trees no longer hold down the soil, river banks increasingly erode as sediment into the water, creating excess nutrients which exacerbate the changes in the river and create problems miles away, in the sea.[21]

Over 95% of forests harvested in Nova Scotia are harvested using the technique of clear cutting. clear cutting a forest involves cutting down virtually every standing tree in a given area, leaving an exposed wasteland of tree limbs and tire ruts where a rich shady forest once stood.[22]

See also

Main article: Outline of forestry

References

  1. ^ a b Dr. J. Bowyer (2009-05-28). "The Power of Silviculture: Employing Thinning, Partial Cutting Systems and Other Intermediate Treatments to Increase Productivity, Forest Health and Public Support for Forestry" (pdf). Dovetail Partners Inc. Retrieved 2009-06-06. {{cite journal}}: Cite journal requires |journal= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
  2. ^ U.S. Environmental Protection Agency, Washington, DC (1992). "Clear cut." Terms of Environment: Glossary, Abbreviations and Acronyms. p. 6. Document no. EPA-175-B-92-001. Accessed 2011-10-12.
  3. ^ Center for Biological Diversity, Tucson, AZ. "Clearcutting and Climate Change." Accessed 2011-10-12.
  4. ^ Global Environmental Governance Project: Forests. [1]
  5. ^ Helms, John A. (1998-09-01). The Dictionary of Forestry. Society of American Foresters. ISBN 978-0-939970-73-5.
  6. ^ British Columbia Ministry of Forests, Victoria, BC. "Clearcut System Variations." Introduction to Silvicultural Systems. Based on the published workbook: "Introduction to Silvicultural Systems, second edition (July 1999)." Forest Practices Branch.
  7. ^ Global Environmental Governance Project: Forests. [2]
  8. ^ Global Environmental Governance Project: Forests. [3]
  9. ^ Forest Encyclopedia Network Advantages and disadvantages of clearcutting
  10. ^ Swanson, F.J.; Dyrness, C.T. (1975). "Impact of clear-cutting and road construction on soil erosion by landslides in the western Cascade Range, Oregon". Geology. 3 (7). Geological Society of America: 393–396. doi:10.1130/0091-7613(1975)3<393:IOCARC>2.0.CO;2.
  11. ^ Toso Bozic (September 14, 2009). "Woodlot Harvest". Government of Alberta: Agriculture and Rural Development. Retrieved 7 March 2011.
  12. ^ Foothill Conservancy, Pine Grove, CA (2001). "Clearcutting in local forests." Foothill Focus. Spring 2001. Accessed 2011-10-12.
  13. ^ Future threats to the Amazon rainforest. [4]
  14. ^ National Geographic:rain forest threats .[5]
  15. ^ Belt, Kevin and Campbell, Robert (1999). "The Clearcutting Controversy - Myths and Facts." West Virginia University Extension Service. Accessed 2011-12-12.
  16. ^ Ottosson Löfvenius, M. (2003). "Snow and Soil Frost Depth in Two Types of Shelterwood and a Clear cut Area". Scandinavian Journal of Forest Research. 18. Taylor & Francis: 54–63. doi:10.1080/0891060310002345. ISSN 0282-7581. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  17. ^ Clearcuts Provide Multiple Benefits to Forests and Wildlife. [6]
  18. ^ Responses of Wildlife to Clearcutting and Associated Treatments in the Eastern United States. [7]
  19. ^ Ancient Forest News - Clearcutting threatens black-tailed deer. [8]
  20. ^ Clearcutting land GreeniacsArticles. [9]
  21. ^ Clearcutting land GreeniacsArticles. [10]
  22. ^ Nova Scotia public lands: Clearcutting. [11]
Wikimedia Commons has media related to Clearcutting.
Look up clear cut in Wiktionary, the free dictionary.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Clearcutting&oldid=524035859"